Download or read book Vortex Excited Unsteady Forces on Resonantly Vibrating Bluff Structures written by Owen M. Griffin and published by . This book was released on 1978 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report considers recent experimental findings pertaining to the vortex-excited oscillations of bluff cylinders, and compares various approaches to measuring the resultant fluid forces. As one example, measurements of the structural damping and crossflow response amplitudes were made for several systems over a representative range of wind tunnel flow speeds. The fluid dynamic damping or reaction in-phase with the cylinder's velocity also was measured for different incident flow speeds over a range which included the locking-on of the vortex shedding to the resonant cylinder vibrations. A mathematical model is proposed in connection with these measurements, and the components of the excitation or lift force on a vibrating structure can be obtained from the model once the structural damping and fluid reaction forces are known. In a second approach, the fluid forces were measured on a cylinder which was forced to oscillate in water at different frequencies and crossflow amplitudes over a range of incident flow speeds. Both the steady and unsteady forces are altered significantly in the locking-on regime, with large amplifications in both the lift and drag. These vortex-excited forces are then incorporated into the mathematical model for self-excited, resonant vibrations and the complementary nature of the two measurement schemes is discussed. The results obtained from the present study are suitable in general for application not only to the vortex-excited vibrations of rigid cylinders, but also to other flexible bluff structures and cables in air and in water. (Author).
Download or read book Vortex Shedding from Stationary and Vibrating Bluff Bodies in a Shear Flow written by and published by . This book was released on 1980 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: If a fluid is in relative motion past a stationary bluff, or unstreamlined, structure and the vortex shedding frequency approaches one of the natural frequencies of the structure, then resonant flow-induced oscillations of the structure can occur when the damping of the system is sufficiently low. These resonant oscillations are accompanied by a 'lock-on' or capture of the vortex shedding frequency by the vibration frequency over a range of flow speeds, and this lock-on effect causes the wake and the structure to oscillate in unison. The periodic lift and the mean drag forces are amplified as a result of the vibrations, and changes in these fluid forces are closely related to the changes that occur in the flow field in the near wake of the body. Many practical ocean and wind engineering situations involve lightly-damped structures that are located in flows of air or water that are nonuniform along the length of the structure. The primary difference between a uniform flow and a shear flow is the presence and added complexity, in a shear flow, of vorticity whose vector is normal to the plane of the flow. When the incident flow approaches the body this vorticity is turned into the flow direction and interacts with the vortices which are shed from the body into the wake.
Download or read book Mechanics of Flow Induced Sound and Vibration Volume 1 written by William K. Blake and published by Academic Press. This book was released on 2017-06-13 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanics of Flow-Induced Sound and Vibration, Volume 1: General Concepts and Elementary Sources, Second Edition, enables readers to fully understand flow-induced vibration and sound, unifying the disciplines of fluid dynamics, structural dynamics, vibration, acoustics, and statistics in order to classify and examine each of the leading sources of vibration and sound induced by various types of fluid motion. Starting with classical theories of aeroacoustics and hydroacoustics, a formalism of integral solutions valid for sources near boundaries is developed and then broadened to address different source types, including jet noise, flow tones, dipole sound from cylinders, and cavitation noise. Step-by-step derivations clearly identify any assumptions made throughout. Each chapter is illustrated with comparisons of leading formulas and measured data. Along with its companion, Mechanics of Flow-Induced Sound and Vibration, Volume 2: Complex Flow-Structure Interactions, the book covers everything an engineer needs to understand flow-induced sound and vibration. This book will be essential reading for postgraduate students, and for engineers and researchers with an interest in aerospace, ships and submarines, offshore structures, construction, and ventilation. Presents every important topic in flow-induced sound and vibration Covers all aspects of the topics addressed, from fundamental theory, to the analytical formulas used in practice Provides the building blocks of computer modeling for flow-induced sound and vibration
Download or read book DTNSRDC written by David W. Taylor Naval Ship Research and Development Center and published by . This book was released on 1984 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1980 with total page 1280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book OTEC Cold Water Pipe Design for Problems Caused by Vortex excited Oscillations written by Owen M. Griffin and published by . This book was released on 1980 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vortex-excited oscillations of marine structures result in reduced fatigue life, large hydrodynamic forces and induced stresses, and sometimes lead to structural damage and to destructive failures. The cold water pipe of an OTEC plant is nominally a bluff, flexible cylinder with a large aspect ratio (L/D = length/diameter), and is likely to be susceptible to resonant vortex-excited oscillations. The objective of this report is to survey recent results pertaining to the vortex-excited oscillations of structures in general and to consider the application of these findings to the design of the OTEC cold water pipe. Practical design calculations are given as examples throughout the various sections of the report. This report is limited in scope to the problems of vortex shedding from bluff, flexible structures in steady currents and the resulting vortex-excited oscillations. The effects of flow non-uniformities, surface roughness of the cylinder, and inclination to the incident flow are considered in addition to the case of a smooth cylinder in a uniform stream. Emphasis is placed upon design procedures, hydrodynamic coefficients applicable in practice, and the specification of structural response parameters relevant to the OTEC cold water pipe. There are important problems associated with the shedding of vortices from cylinders in waves and from the combined action of waves and currents, but these complex fluid/structure interactions are not considered in this report.
Download or read book Symposium on Flow Induced Vibrations Excitation and vibration of bluff bodies in cross flow written by M. P. Paidoussis and published by . This book was released on 1984 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 1048 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Review written by and published by . This book was released on 1978 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow induced Vibrations written by and published by . This book was released on 1979 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the 6th Ocean Thermal Energy Conversion Conference written by and published by . This book was released on 1979 with total page 610 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Preprints written by Gordon L. Dugger and published by . This book was released on 1979 with total page 830 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanics of Flow Induced Sound and Vibration V1 written by William K. Blake and published by Elsevier. This book was released on 2012-12-02 with total page 459 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanics of Flow-Induced Sound and Vibration: Volume 1 discusses a broad selection of flow sources that are widely encountered in many applications of subsonic flow engineering and provides combined physical and mathematical analyses of each of these sources. It classifies each of the leading sources of vibration and sound induced by various types of fluid motion and unifies the disciplines essential to describing each source. The book considers sources such as jet noise, flow-induced tones and self-excited vibration, dipole sound from rigid and flexible acoustically compact surfaces, random vibration of flow-excited plates and cylindrical shells, cavitation noise, acoustic transmission characteristics and sound radiation from bubbly liquids, splash noise, throttling and ventilation system noises, lifting surface flow noise and vibration, and tonal and broadband sounds from rotating machinery. It also integrates the fundamentals of the subject with the many practicalities of the design of quiet vibration-free machinery. This book caters to advanced students well-versed in applied mathematics, fluid mechanics, and vibrations, strength of materials, acoustics, and statistical methods.
Download or read book The Effects of Vortex Coherence Spacing and Circulation on the Flow Induced Forces on Vibrating Cables and Bluff Structures written by S. E. Ramberg and published by . This book was released on 1976 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vortex wake of a vibrating flexible cable was studied by means of velocity measurements and correlation, frequency spectra, and flow visualization. Three distinct spanwise regimes were identified according to wake structure. Near the cable nodes the flow resembles that of a stationary cable. Adjacent to the node is a transition regime which extends up to the locked-in or synchronized wake flow about the cable antinode. Each regime was characterized by spectral content, degree of spanwise correlation, and local vortex street geometry. Measured downstream velocity profiles and vortex spacing were matched with a mathematical model to obtain the vortex strength and its relation to cable vibration conditions. The von Karman drag formula was used to compute the steady drag coefficients directly, and the distributions of fluctuating lift and drag were inferred from the data. The vortex strength and fluid forces on the vibrating cable were found to be as much as 65 percent larger for locked-in conditions than in the stationary case. Where comparisons were possible, there was good agreement between present results and previous results for vortex-excited rigid cylinders, including some direct measurements of the increased drag. (Author).
Download or read book A Modern Course in Aeroelasticity written by E.H. Dowell and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aeroelasticity is the study of flexible structures situated in a flowing fluid. Its modern origins are in the field of aerospace engineering, but it has now expanded to include phenomena arising in other fields such as bioengineering, civil engineering, mechanical engineering and nuclear engineering. The present volume is a teaching text for a first, and possibly second, course in aeroelasticity. It will also be useful as a reference source on the fundamentals of the subject for practitioners. In this third edition, several chapters have been revised and three new chapters added. The latter include a brief introduction to `Experimental Aeroelasticity', an overview of a frontier of research `Nonlinear Aeroelasticity', and the first connected, authoritative account of `Aeroelastic Control' in book form. The authors are drawn from a range of fields including aerospace engineering, civil engineering, mechanical engineering, rotorcraft and turbomachinery. Each author is a leading expert in the subject of his chapter and has many years of experience in consulting, research and teaching.
Download or read book Journal of Applied Mechanics written by and published by . This book was released on 1979 with total page 1002 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publishes original research in all branches of mechanics including aerodynamics; aeroelasticity; boundary layers; computational mechanics; constitutive modeling of materials; dynamics; elasticity; flow and fracture; heat transfer; hydraulics; impact; internal flow; mechanical properties of materials; micromechanics; plasticity; stress analysis; structures; thermodynamics; turbulence; vibration; and wave propagation.
Download or read book Flow induced Vibrations an Engineering Guide written by Eduard Naudascher and published by Routledge. This book was released on 2017-11-13 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designed for engineers, this work considers flow-induced vibrations. It covers topics such as body oscillators; fluid loading and response of body oscillators; fluid oscillators; vibrations due to extraneously-induced excitation; and vibrations due to instability-induced excitation.
